JPS6086881A - Manufacture of electrostrictive-effect element - Google Patents

Abstract

PURPOSE:To form a dense glass coated film and to enhance the insulating withstand voltage of an electrostrictive-effect element by a method wherein the grain size of glass powder in a suspension, which is made to stick to the exposed parts of internal electrode layers by an electrophoresis method, is set at a value in a specific extent. CONSTITUTION:A laminated body constituted by alternately laminating internal electrodes 3 and 4 and electrostrictive material 1 and 2 is manufactured in such a way that the internal electrodes 3 and 4 are made to expose at the surface and the back surface of the laminated body. The electrodes 3 and 4 are made to alternately connected with temporary electrodes 5 and 6 provided on both sides of the laminated body every one layer. The laminated body is installed in a suspension containing glass powder, the value of the electified BET specific surface area of which is a grain size of 1.0-2.0m<3>/g, along with an opposed electrode plate (not shown in the diagram). At this time, one side of the laminated body is ready for having been covered with an adhesive tape. DC voltage is impressed in between the electrode 5 and the opposed electrode plate, and glass powder 7 is made to stick to the internal electrodes 3 and the electrostrictive material in the vicinites of the internal electrodes 3. When the laminated body obtained in such a way is baked, a dense glass coated film having a high insulating withstand voltage can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing an electrostrictive element using longitudinal effect.

In the structure of an electrostrictive effect element that utilizes the longitudinal effect, in order to prevent stress concentration when strain occurs by generating an electric field throughout the electrostrictive material, it is possible to have poles within the same size as the entire cross section of the element. is necessary.

In order to generate a high electric field at a very low voltage and obtain a large strain, it is necessary to set the interval between the internal electrodes to about 100 microns. In the above two manifestations, the internal electrode has the same area as the cross section of the element. It is very difficult to electrically connect electrostrictive elements.

Therefore, the present inventors first developed an electrical connection method characterized by forming an insulator every other layer on the internal electrode layer exposed on the end face of the electrostrictive material laminate and the ceramic in its vicinity by electrophoresis. proposed.

FIG. 1 is an external view of an electrostrictive effect element connected by this method. An insulator 7 is deposited every other layer on the exposed inner electrode layer and the ceramic in its vicinity by electrophoresis.
is formed. An insulator 8 is also formed on the inner electrode shifted by one layer on the end face on the back side. A band-shaped external electrode 11 is formed across this insulator and the exposed internal electrode 4. Similarly, on the back side, every other external terminal for the internal 11 poles 3 is connected to a positive terminal 13 or a negative terminal 12, respectively. By applying a DC voltage between these external terminals, the electrostrictive material 2 excluding the protective film portion 1
A uniform electric field is generated over the entire area, and the element is elongated in parallel to the stacking direction. Since there is no stress concentration, the element will not be destroyed even if voltage is repeatedly applied, and since the internal electrode distance is about 100 microns, it can be driven at a low voltage of 100 microns or less.

A method for manufacturing this element will be briefly explained.

First, a laminated body as shown in Fig. 2 is fabricated by applying the manufacturing technology of a multilayer ceramic capacitor, in which the inner layer 3.4 and the layer 2 are alternately layered on an electrostrictive material.

A large number of internal electrodes 3.4 are exposed on the front and back end surfaces, and are alternately connected to two temporary external electrodes Wi 5.6 formed on the side surfaces at every other layer. Place this laminate and an opposing '4' FM metal plate in the suspension, and set the DC voltage to this level! When a voltage is applied from the electrode plate toward the temporary outer st pole 5, the positively charged glass powder in the suspension adheres to the electrostrictive material inside [413 and its vicinity] by electrophoresis. FIG. 3 is an external view of a laminate with glass powder adhered to the front end face. In the figure, numeral 1 indicates an electrostrictive material that functions as a protective film, and numeral 2 indicates an electrostrictive material in a portion where an electric field is generated to cause distortion. 4 indicates exposed internal electrodes, and the internal electrodes existing between them are covered with glass powder 7. After the glass powder is baked and fixed, the glass powder is applied to the back end face in the same manner and fixed by baking. The laminated body formed with the insulator is cut at the positions shown by broken lines in FIG. 4, and external electrodes 11 are formed on several small pieces 1o excluding the small pieces 9 at both ends, resulting in the electrostrictive effect element shown in FIG. 1. is obtained.

Problems with this method include that the width and thickness of the deposited glass powder vary greatly, and that pores are sometimes generated after firing, making the glass coating porous and greatly reducing the dielectric strength. The width and thickness of the adhesion are determined by the ease of adhesion, which is proportional to the amount of charge per unit amount of glass powder, and fine glass powder with a large specific surface area can be made to have sufficient width and thickness in a short time. Adhesion is obtained. The second problem is related to the defoaming properties of the glass powder during firing. In the case of coarse glass powder, bubble removal is good and a dense glass coating can be obtained, but in the case of fine glass powder, the bulk density is low and sintering takes place with a large number of bubbles trapped, resulting in a porous glass coating.

This phenomenon is thought to be particularly noticeable in the case of fine band-shaped glass powder.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing an electrostrictive effect element that has sufficient width and thickness and can form a band-like adhesion of glass powder that is easily degassed during firing to form a dense glass coating. It is.

The method of the present invention involves the use of an electrostrictive material in a suspension containing electrically charged glass powder. All or part of the internal electrode layer of the laminated body with the electrode is used as one layer of electrode, and the counter electrode plate is used as the other layer of electrode.
A DC voltage is applied between both electrodes as j4M, and the charged glass powder is transferred to the inside of the surface of the laminate by electrophoresis. In the method for producing an electrostrictive effect element in which the exposed part of the pole layer 0) the part or a part thereof and its surroundings θ) the electrostrictive material FLr is attached, the glass powder has a BFiT specific surface area of 1.0 to 2. 0 is a desirable range. BET specific surface area is 1. Coarse raw material powder having a particle size of less than Onl'/g can be easily adjusted to a particle size of about 1.5♂/g by adding ethanol and wet-pulverizing it for a predetermined period of time in an alumina ball mill. Since pulverization also has the effect of activating the powder, a better glass coating can be obtained by wet-pulverizing coarse raw material powder.

The adhesion properties of glass powder during electrophoresis and the defoaming properties during firing are inversely related to each other using the particle size of the glass powder as a parameter. It is not possible to stably form a glass coating with a high dielectric strength.

The present invention will now be described in detail with reference to Example ti.

First, a large number of interior parts of the structure shown in FIG. 2 are fabricated using an electrostrictive material having poles and a set of temporary external electrodes as described below.

Magnesium lead niobate (Pb(Mg1/3Nb2/3
)08) and lead titanate (PbTi03) as main components, a small amount of an organic binder was added to a powder of a strained material, and a slurry was prepared by dispersing this in an organic solvent. This slurry was coated onto a Mylar film to a thickness of about microns using a casting film forming apparatus used in the production of conventional V4) WrI ceramic capacitors, and then dried and smoked. This was peeled off from the film to obtain an electrostrictive material green sheet. Some of the green sheets were screen printed with platinum paste as internal electrodes. Several tens of these green sheets were assembled, pressed into one piece using a hot press, and then fired at 1250°C to obtain a compact strained material. This is cut at a position where the internal electrodes are exposed on the surface every other layer, temporary external electrodes are applied and baked, and the side surfaces are cut to form a laminate with the internal IT electrodes exposed as shown in Figure 2. Obtained. Electrophoresis is applied to the m-layer electrostrictive material thus obtained. In FIG. 2, numeral 1 indicates the electrostrictive material of the protective film portion, and numeral 2 indicates the electrostrictive material that causes strain. The inner electrodes 3.4 are connected to temporary outer electrodes denoted 5 and 6, respectively, and the other inner electrodes are connected alternately every other layer.
connected to two temporary external electrodes.

Next, five types of zinc borosilicate crystallized glass powders with different particle sizes were prepared. The raw material powder has a BET specific surface area of 0.3
It was pi/g. 300g of this raw material powder is mixed with 60g of ethanol.
0m/ in an alumina ball mill for 4 hours, and the BET specific surface area Q, 7 n? /g of glass powder was obtained. 8 hours, 12 hours, 16 hours in the same way
time, 1.0♂ each from 20 hours of grinding
/g, 1.5 dlg, 2.0 dlg.

A glass powder of 2.8♂/g was obtained.

The adhesion and sinterability of the five types of glass powders having different particle sizes were investigated by electrophoretic adhesion and sintering experiments using the electrostrictive material laminate using the method described below.

Wet-milled zinc borosilicate crystal glass powder 3
0g, ethanol 290mA! , 10 ml of 5% iodine ethanol solution are mixed in a high speed hosegenizer. Iodine acts as an electrolyte, and the glass powder is positively charged. (9) After applying ultrasonic waves for one minute, leave to stand for 30 minutes to remove the precipitate, and use the remaining suspension.

FIG. 5 shows how to connect the electrophoresis device.

One side of the electrostrictive material laminate 21 where the internal electrodes are exposed is covered with adhesive tape to prevent it from getting wet with the suspension, and then submerged in the container 22 filled with the suspension. A cylindrical stainless steel counter electrode is submerged at a distance of 1cIIL from the surface to which it is to be attached. The counter electrode is connected to the positive terminal of a DC power supply, the temporary external electrode is connected to the negative terminal, and a DC voltage of (2) is applied. Dry after finishing. After removing the adhesive tape on the back side, it is held at 705 t: and fired to form a glass film. The glass coating was cut using an internal blade cutting method, and the cross section was observed to check for the presence of internal pores.

The table summarizes the results of adhesion and firing experiments conducted using this method. The adhesion time term is the time required to obtain a sufficient width, and is set to 0 if a short time is sufficient. Coarse glass powder was marked with an X because the glass powder settled in the container during the experiment and caused problems. With very fine glass powder, defoaming is not possible even if held at the softening point for a long time, but with glass powder marked with an O mark, defoaming is possible by holding the glass powder at a softening point of around 600°C for about 4 hours. It became. From the results shown in the table, 1. It can be seen that in a range smaller than Onr/g, the adhesion is poor, and in a range larger than 2.0♂/g, the sinterability is poor. Therefore, the particle size of the glass powder should be adjusted to a BET value of 1.0 to 2.0 ml'/g.

The method of the present invention for adjusting the particle size of glass powder makes it possible to form a dense glass coating with sufficient width and thickness on the exposed portion of the internal electrode on the end face of the electrostrictive material laminate by electrophoresis. This makes it possible to electrically connect electrostrictive elements stably and with high reliability.

[Brief explanation of drawings]

Diagram M1 is an external view of an electrostrictive effect element in which electrical connections are made using an insulating film using an electrophoresis method. Number 1 in the diagram
2 shows the electrostrictive material of the protective film portion, 2 the electrostrictive material of the part where strain is generated, 3.4 the internal electrode, and 7.8 the insulating film formed by electrophoresis. 11 is an external electrode, 12.1
3 indicates external connection terminals on the negative side and the positive side, respectively. FIG. 2 is an external view of an electrostrictive material laminate with temporary external electrodes for applying the electrophoresis method. In the figure, number 5.6 indicates a temporary outer electrode which interconnects the inner electrodes. FIG. 3 is an external view showing an electrostrictive material laminate in which glass powder is deposited every other layer on the internal electrode exposed portion and the surrounding ceramic. Number 7 in the figure indicates the attached glass powder. FIG. 4 is an external view showing the cutting position (point #) of an electrostrictive material laminate with glass coatings formed on both end faces. In the figure, number 9 indicates a small piece at both ends that cannot be used, and lO indicates a portion that can be used as an electrostrictive effect element. FIG. 5 is an external view showing how to connect the electrophoresis device. In the figure, number 21 is the electrostrictive material laminate, 22 is the container, and n is the circle i.
The mold counter electrodes are shown respectively. or a DC power source; 25 is a positive terminal; 27 is a negative terminal; and 27 is a ring for interconnecting conductive wires. Fig. 1 3 Fig. 2 Fig. 3 Fig. LI-Fig. n Fig. 5 4

Claims (1)

[Claims] All or part of the internal electrode layer of a laminate of an electrostrictive material and an electrode inside in a suspension containing charged glass powder is used as one layer of electrodes, and the counter electrode plate is used as the other electrode between both electrodes] l(
Electrostriction comprising the step of applying a current voltage and depositing the charged glass powder on all or part of the exposed portion of the internal electrode layer on the surface of the laminate and the electrostrictive phase material around it by electrophoresis. In the method for manufacturing an effect element, the glass powder has a specific surface area of B E 'i' of 1, θ to 2.
A method for manufacturing an electrostrictive element, characterized by using powder having a particle size of Orl/g O).